ios reminders not updating

Hi

I have my mac and iPhone 4S (on ios7) syncing through icloud.

Whilst my mac syncs perfectly with icloud, my iphone doesn't keep updated with changes. It seems really erratic and eventually it might update itself, but it doesn't do an automatic update on opening Reminders for example, which is where I'm seeing the problem.

It means that my iPhone brings scheduled reminders up, even though I deleted them some time ago on my mac and then change was reflected in icloud online.

Any suggestions, or is this another bug to be fixed?

Mark